Re: How many colors does a rainbow have? (8)

[tye]

I voted 6 because I never saw the point of separating "Indigo" and "Violet" (and ROYGBP maps nicely to three primary colors plus three secondary colors).

Then I searched around for some decent pictures of real rainbows. At first this confirmed my previous impressions; they all looked like they went from "Blue" to "Purple" then ended.

They also ran quite suddenly from "Red" to "Yellow" making "Orange" rather hard to pick out while "Green" through "Blue" were clearly not sufficiently represented in "ROYGBIV".

After reviewing several pictures of rainbows in the sky and from prisms, the best list of colors I could come up with was: Red, Orange, Yellow, Green, Teal, Cyan, Blue, Purple. The only picture that gave me an impression of separating "Purple" into "Indigo" plus "Violet" was http://people.rit.edu/andpph/photofile-c/prism-DSCN4982.jpg. Perhaps it is just that "Violet" tends to be quite faint.

Update: Then I went to look for cannonical examples of "Indigo" and "Violet" and found confirmation of my first point:

Although traditionally considered one of seven divisions of the optical spectrum, modern color scientists do not usually recognize indigo as a separate division and generally classify wavelengths shorter than about 450nm as violet.

This was immediately followed by something that was educational to me:

Indigo and violet are different from purple, which cannot be seen on the electromagnetic spectrum but can be achieved by mixing mostly blue and part red light.

Which rather reminded me of the term "monkey". Practicing biologists know that humans and (other) apes are not monkeys while non-biologists know that apes are a type of monkey (as are humans). I know that the color at the end of the rainbow is a shade of purple, despite what practicing spectrumists might believe. :)

Update: Actually, "Green" is still insufficiently represented. ... Yellow Lime Green Teal Cyan Blue ... seems more accurate. (Leprechauns++)

[freakingwildchild]

http://en.wikipedia.org/wiki/Visible_spectrum would give 6 colors,
http://en.wikipedia.org/wiki/Rainbow would give 7 colors ...

Place your bets!

In the rgb theory the prisma could also have 6768-1 colors, refered to http://upload.wikimedia.org/wikipedia/commons/thumb/f/fc/Spectre.svg/744px-Spectre.svg.png

I've just been counting the colors in the visible spectre image below, 6768 colors including the black waveline... but I think I'm just pulling the line a bit too much now ;)

Personally I think infinity-1, with 7 distinct visible differences.

[prysmatik]

I saw a great video once about how Blue & Red form purple. Basically that it's an imaginary color or some such made up by the brain.

"The Mystery of Magenta"

Not trying to advertise content or what not, so I guess I'll leave it to you to search it out.

But I found it interesting.

Basically something about how we're connecting 2 ends of the color spectrum by going the OTHER way.